The 300 exc has plenty of power. Three of my buddies ride them ('99 and '00 models), mainly in the woods. All did some fine tuning on the jetting.
As delivered from KTM, the powervalve opens pretty early and gives a strong midrange hit. The guys I know adjusted the powervalve spring so that the powervalve opens later. This results in plenty of strong low end and mid range for tight trails with a super top end when things open up. A side benefit of cleaning the jetting up and opening the PV later is better fuel mileage.
The motor is so strong down low that 2nd and some clutch will get you up just about anything. As far as gaps between ratios, it is strictly personal preference between EXC and MXC - the motor easily pulls the gaps, IMO.